Rotary gas switch,in particular for water heaters



United States Patent Inventor Gerhard Schueler Remscheid, Germany Appl. No. 767,265 Filed Oct. 14, 1968 Patented Dec. 29, 1970 Assignee Joh. Vaillant KG.

Remscheid, Germany Priority Nov. 25, 1967 Germany No. 1,629,884

ROTARY GAS SWITCH, IN PARTICULAR FOR WATER HEATERS (inquired);236/15A,(1nquired); 126/351, 374, (lnquired); 137/65, 66, 628, 636, 636.1, 636.4, 630.19

[56] References Cited UNITED STATES PATENTS 2,591,897 4/1952 Weber et al. l37/66 FOREIGN PATENTS 1,059,857 6/1959 Germany 137/66 Primary Examinerwilliam F, O'Dea Assistant ExaminerRichard Gerard Att0rne vDarbo, Robertson & Vandenburgh ABSTRACT: Axially aligned are a pilot gas valve closure and a main gas valve closure. A limited amount of axial movement of a valve shank first opens the pilot closure and more movement subsequently the main closure. Upon rotation of a cam disc in one direction, a cam pair on the body and disc forces the disc axially of the shank into, and along with, a cam support which also is rotated by the rotation of the cam disc. The cam support moves the valve shank. A thermally sensitivelatching apparatus holds the cam support in the rotated position and thereafter a reverse rotation of the cam disc additionally cams the cam support in the axial direction of the valve shank to open the main gas valve.

PATENTED 050291970 same 0F 2 INVEN 'I'OR:

02 -[/v6. GE/FH/WD Sam/L El? ROTARY GAS SWITCH, IN PARTICULAR FOR WATER HEATERS This invention relates to a rotary gas switch, in particular for water heaters with coaxially disposed ignition gas valve and main gas valve, adapted to be successively opened by the lift (i.e. axial movement) of a valve shank which is provided with a driver. It is known in such rotary gas switches to control the lift of the valve shank by a rotatably and slidably disposed cam support which can be rotated by a rotary handle and by means of a control cam mounted thereon and can be locked in the rotated position and against the action of a return spring by thermally sensitive-locking means, the main gas valve being opened by reverse rotation of the rotary handle by virtue of the control cam sliding on a lifting cam of the interlocked cam support to produce an axial displacement thereof.

In rotary gas switches which operate in this manner German Pat. 1 059 857) interlocking of the cam support while the ignition gas valve is opened permits an ignition safety device, for example thermoelectric, to be mounted for acting upon the interlocking system. The object of the invention is to improve a rotary gas switch as set forth above and to perfect it, in particular to facilitate production and to improve the functional reliability.

According to the present invention the rotary handle is associated with a disc cam which supports the control cam, said disc cam bearing on thecam support and cooperating with an inclined surface, which is fixed relative to the housing, so that rotation of the rotary handle causes the same and the cam support to be axially displaced by an amount which is sufficient for opening the ignition valve. The cam for producing the lift required for opening the ignition valve is therefore not mounted on the rotatable cam support, instead a separate disc cam is provided and mounted on the rotary handle and said rotary handle is adapted to be axially displaceable. This offers the advantage that the valve shank can bear centrally on the cam support and its contact surface may be rendered adjustable, for example by means of an adjusting screw.

The rotary gas switch may be further improved by providing the cam support with a radially extending extension which cooperates with a three-armed, pivotably disposed bolt lever in such a manner that striking the extension on the middle lever arm causes the bolt lever to be pivoted until a hookshaped end of the outer lever arm grips over the extension, the third lever arm thus entering the zone of thermally sensitive retaining means. Appropriately, the return spring of the cam support may be constructed as a spiral spring which is stressed during rotation but also induces axial displacement of the cam support. A resilient ring for damping the return motion of the cam support may be disposed between the disc cam of the rotary handle and the cam support.

The thermally sensitive interlocking means may comprise two independently responding thermally sensitive elements which act nonpositively on to a bolt lever. The interlocking system for the rotary gas switch may be triggered either by an ignition safety system, for example thermoelectric, or by a thermostat responding to the water temperature, thus making it possible to dispense with additional safety valves.

The invention is illustrated by way of example in the accompanying drawings, in which:

FIG. 1 is a sectional elevation of the rotary gas switch;

FIG. 2 is a section along the line A-A of FIG. 1;

FIG. 3 is a front view of the rotary gas switch;

FIG. 4 is a section through the gas switch in the ignition position;

FIG. 5 is a section along the line 8-8 of FIG. 4;

FIG. 6 is a front view in the ignition position;

FIG. 7 is an embodiment with an additional thermostat, and

FIG. 8 is a section along the line C-C of FIG. 7.

A spring-biased ignition gas valve closure 2 and a main gas valve closure 3, also spring-biased, are coaxially disposed in a housing 1. A valve shank 4 has a driver 4' and is guided in the housing 1. Axial movement by the shank 4 successively opens the valve closures 2, 3 against the action of valve springs an gas pressure. An ignition gas duct 5 branches off between the closures 2, 3. The valve shank 4 is disposed at the bottom of a cup-shaped cam support 6 having a tubular extension 6'. An adjusting screw 7, representing an adjustable stop surface for the valve shank 4, is disposed in the extension 6'. The cam support 6 is disposed in the housing 1 coaxially to the valves 2, 3 and is axially slidable and rotatable. A helical spring 8, surrounding the valve shank 4, is mounted on the one hand on the housing 1 and on the other hand on the cam support 6 thus counteracting rotation as well as axial displacement of the cam support 6. A rotary handle 9, fixedly joined to a disc cam 10, is pushed over the extension 6' of the cam support 6. Said disc cam 10 bears via an intermediate resilient damping ring 11 on the cam support 6 and is guided in cup cover 12 screwed onto the housing 1, The disc cam 10 is provided with a cam 16' which cooperates with an inclined surface 13 in the interior of the cup cover 12. Rotation of the rotary handle 9 causes said handle together with the cam support 6 to be axially displaced (to the left in FIGS, 1 and 4) so that the ignition gas valve closure 2 is opened. The lift is limited by virtue of the fact that the disc cam 10 contacts an end face 1' of the housing 1. The disc cam 10 has a control cam 14 which on rotation of the rotary handle 9 causes the cam support 6 to be also rotated against the action exerted by the helical spring 8. The cam support 6 has a radial extension 15 which assumes the position shown in FIG. 2 in broken lines when the rotary handle 9 is rotated. This is the case when the rotary handle 9 is rotated through more than from the full line position shown in FIG. 3 into the full line position I (ignition position) shown in FIG. 6. A three-armed bolt lever 16 is journaled in the housing 1 at 16'. The radial extension 15 which bears on the middle arm of the bolt lever 16, causes the bolt lever 16 to be slightly pivoted counterclockwise, assisted by a spring 17 and against the action exerted by a spring 18, so that the hookshaped outer lever arm reaches over the extension 15 thus preventing reverse rotation of the cam support 6 (FIG. 5). A pin 19 bears nonpositively on the third arm of the bolt lever 16 owing to the effect of the spring 18. The pin 19 supports the armature 20 of a thermoelectrically excited retaining magnet 21. In the ignition position shown in FIG. 5 the bolt lever 16 has overcome the force exerted by the spring 18 and has placed the armature 20 against the poles of the retaining magnet 21. Since the ignition valve 2 is opened it is possible for an ignition flame, which is not shown, to be ignited. In a known manner, the ignition flame heats a thermocouple (not shown) which produces the excitation current for the retaining magnet 21l While the retaining magnet 21 is energized by the burning of the ignition flame, the armature 20 will be retained against the action exerted by the spring 18. When the rotary handle 9 is rotated it remains in its position because the bolt lever 16 retains the cam support 6 in the rotated position against the urging of the helical spring 8. If the ignition flame is extinguished and therefore the excitation of the retaining magnet 21 collapses, the spring 18 resets the bolt lever 16 and, from led the rotary handle 9 is released, and the helical spring 8 returns the cam support 6 and the rotary handle 9 into the starting position (0 position) so that the ignition gas valve is once again closed.

Opening of the main gas valve 3 is possible only if the cam support 6 is retained in its rotated position and in the manner described by means of the bolt lever 16. If the rotary handle 9 is then slightly reversed from the ignition position I into position II (dotted lines in FIG. 6) the cam 14 will slide on a lift cam 22 of the rotated cam support 6 to displace said support 6 in the axial direction while opening the main gas valve 3. The extension 15 will thus slide axially of the valve along the bolt lever 16 (while still being held thereby) until the cam 14 reaches a ratchet condition in position II at cam area 23. If the rotary handle 9 is rotated beyond the position ll into the position 0, the cam 14 will slide on a further lift cam 24 of the cam support 6 thus displacing said support 6 by a further amount in the axial direction (to the left). The bolt lever 16 will however slide off the extension 15 at the right hand end thereof, as seen in FIG. 1, so that the spiral spring 8 is then able to rotate and slide the cam support 6 into the original position shown in FIG. 1 so that both valves 2 and 3 are closed. This procedure takes place irrespective of whether the retaining magnet 21 is still energized. The bolt lever 16 is retained by the compression spring 17 in its position illustrated in FIG. 5. By rotating the rotary handle 9 into the position it is therefore possible for the gas valves 2, 3 to be closed at any time, even if the ignition flame is alight.

In the embodiment illustrated in FIGS. 7 and 8 it is possible, when the retaining magnet 21 releases, for the bolt lever 16 to be triggered by the spring 18 as previously described. Also, bolt lever 16 may be triggered by a monitoring thermostat to be described hereinbelow so that the two valves 2, 3 of the rotary gas switch are made to close. A monitoring thermostat in he form of an expansion vessel connected to a thermal sensing element (not shown) by means of a capillary tube 25' is disposed in a sleeve-shaped housing extension 26. The expansion vessel 25 acts upon a rocker lever 28 joumaled in the housing extension 26 at 27. Lever 28 has a ratchet pin 29 which extends into an opening 30 of a control lever 31 to engage the lever 31. The control lever 31 is joumaled at 32 in the housing 26 and one end 33 of the control lever 31 extends from said housing. The control lever 31 reaches under the bolt lever 16 and is biased by a control spring 34. As soon as a predetermined temperature on the thermosensing element is exceeded the expansion vessel 25 fires the rocker lever 28 thus disengaging the ratchet pin 29 from the opening 30 of the control lever 31 to release the control lever. The force exerted by the spring 34 and previously retained by the ratchet pin 29 is thus released so that the control lever 31 can trigger the bolt lever 16. If rotation of the rotary handle 9 causes the bolt lever 16 to be moved into the interlocking position when the switch is turned on again, it will be necessary to overcome the switch spring 34 in addition to the spring 18 until, after cooling of the expansion vessel 25, the ratchet pin 29 can reengage in the opening 30 of the control lever 31. Means may be provided to ensure that'this action does not take place by itself but instead the switch lever 31 will have to be moved manually be means of the extending end 33 into a certain position after the cause of a defect has been removed.

1. A rotary gas switch for water heaters, comprising a valve housing, coaxially disposed ignition valve and main gas valve in the housing, and means for successively opening said valves, including a valve shank, a rotatably and slidably disposed cam support for controlling the lift of said shank mounted for axial displacement relative to the valve shank axis, a rotary handle for rotating said cam support, a cam disc associated with said handle. a control cam on said cam disc, and thermally sensitive means for locking said cam support in a first rotated position and against the action of a return spring, said cam disc bearing on said cam support and cooperating with an inclined surface which is fixed relative to the valve housing so that rotation of said rotary handle and cam support to said first position causes said handle and said cam support to be displaced axially by an amount sufficient to open the ignition valve, reverse rotation of said handle from said first position causing the control cam to slide on a lifting cam of the locked cam support to produce further axial displacement thereof sufficient to open the main gas valve.

2. A rotary gas switch according to claim 1, wherein the thermally sensitive means includes a three-armed pivotably journaled bolt lever and a thermally sensitive-retaining device, said cam support has a radially extending extension which cooperates with said bolt lever so that striking of the said extension on the middle lever arm causes the said bolt lever to be pivoted until a hook-shaped end of the outer lever arm reaches over the said extension, the third lever arm moving into the zone ofthermally sensitive-retaining device.

3. A rotary gas switch according to claim 1, wherein the return spring of the cam support is constructed as a helical spring. stressable by rotation but also causing axial displacement of the said cam support.

4. A rotary gas switch according to claim 1, wherein a resilient ring for damping the return motion of the cam support is disposed between the disc cam of the rotary handle and the said cam support.

5. A rotary gas switch according to claim 1, wherein the thermally sensitive-means comprise two independently responding thermally sensitive elements which bear against a bolt lever.

6. A rotary gas switch according to claim 1, wherein the thermally sensitive-means comprise two independently responding thermally sensitive elements which bear against a bolt lever and wherein the bolt lever has a third lever arm acted upon by the return spring of an armature of a thermoelectrically energized magnet and by the spring of an interlocked lever whose interlocking can be released by a monitoring thennostat.

7. In a rotary gas switch for a water heater or the like having a thermally sensitive device actuated by the burning of an ignition flame, said switch having coaxially disposed ignition gas valve and main gas valve mounted in a housing for axial movements to open the valve, valve shank means associated with said valves to actuate the valves and a valve operator device mounted in the housing and having a portion operatively connected to the valve shank to control the axial movement of the shank and valves, the improvement in said valve operator device comprising:

cam support means mounted for rotary motion about an axis and for sliding motion along said axis, said cam support means forming said portion for controlling the movement of the shank and valves, said sliding motion along said axis being from an initial position at which both valves are closed to a first displaced position at which only the ignition gas valve is open to a second displaced position at which both gas valves are open, said cam support means being rotatable in a given direction between a first rotational position and a second rotational position and in the reverse direction between said second position and the first position;

a return spring engaging said housing and said cam support means to resiliently urge said cam support means to said first position;

latching means operatively associated with said thermally sensitive device and having a part positioned to engage said cam support means when it is in said second position and to retain said cam support means in said second position against said urging when said thermally sensitive device is actuated;

a cam disc mounted in juxtaposition to said cam support means and for rotary motion about said axis and for sliding motion along said axis, said cam disc having a handle by which the disc can be rotated;

first cam means having a portion on said housing and a portion on said cam disc for, when said cam disc is rotated a given amount in said given direction, displacing said cam support means along said axis from said initial position to the first displaced position to thereby move said shank and open said ignition valve so that said ignition flame may be ignited; and

second cam means having a part on said cam support means and a part on said cam disc for rotating said cam support means from said first rotational position to said second rotational position as said cam disc is rotated said given amount in said given direction whereby, with the burning of said ignition flame, said latching means will hold said cam support means in said second position, and for moving said cam support means from said first displaced position to the second displaced position in response to reverse rotation of said cam disc means while said latching means holds said said cam support means at said second rotational position whereby said further movement of said cam support means will correspondingly move said valve shank and open said main gas valve.

8. In a gas switch as set forth in claim 7, wherein said latching means is disengaged by movement ofthe cam support with the shank and cam disc, said cam disc having an axial opening, said cam support means including an adjusting screw in said extension and in contact with said shank, said screw being accessible from the opposite side of said disc from said cam support.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,550,603 Dated December 29, 1970 Inventofl Gerhard Schuler It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Name, Gerhard "Schueler" should be Schuler Col. 2, line 57, "from led should be provided Col. 2, line 57, delete "and".

Col. 3, line 27, "fires" should be pivots Col. 3, line 39, "be" should be by Col. 4, line 70, after "holds" delete said Signed and sealed this 1 7th day of August 1971 (SEAL) Attest:

EDWARD M.FLETCI-IER.JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents 

